PileLAT program adopts the p-y curve model of liquefied sand recommended in Rollins (2005) based on the full-scale lateral load tests to analyze the laterally loaded single piles when the liquefied sand layer is present.

The typical p-y curve for liquefied sand is shown in the figure below. The pile lateral soil resistance, P, increases with the pile deflection along a concave upward curve until the deflection reaches 150 mm. Note that Pu is the ultimate lateral resistance when the pile deflection (y value) is equal to or greater than 150 mm.

The following equations are proposed by Rollins et al. (2005) to estimate the mobilization of pile lateral soil resistance (P) with deflection (y):

Note that A, B, and C in the equations above are the curve fitting parameters that depend on the depth (X). D is the pile diameter. Pd is the pile diameter correction factor and it is limited to the pile diameter between 0.3 m and 2.6 m.

The following figure shows the input requirements for the liquefied sand p-y curve model in the PileLAT program. The only input parameter required is the total unit weight which is used to calculate the vertical total stress within the foundation.

Typical p-y curves for the liquefied sand model are shown in the figure below as part of the analysis outputs for the analysis example where the liquefied sand p-y curve model is used.